Updated XHR API so call sites are more descriptive.

remoting/webapp/crd/js/host_list_api_impl.js

Index: remoting/webapp/crd/js/host_list_api_impl.js
diff --git a/remoting/webapp/crd/js/host_list_api_impl.js b/remoting/webapp/crd/js/host_list_api_impl.js
index 838bafa9e6d0a46b9cb7eac776a1e7452f73f149..f82ad1a1a9fbf08c3b1817600988987adb1c45a2 100644
--- a/remoting/webapp/crd/js/host_list_api_impl.js
+++ b/remoting/webapp/crd/js/host_list_api_impl.js
@@ -26,17 +26,16 @@ remoting.HostListApiImpl = function() {
  * @param {function(!remoting.Error):void} onError
  */
 remoting.HostListApiImpl.prototype.get = function(onDone, onError) {
-  /** @type {function(XMLHttpRequest):void} */
+  /** @type {function(remoting.Xhr.Response):void} */
   var parseHostListResponse =
       this.parseHostListResponse_.bind(this, onDone, onError);
   /** @param {string} token */
   var onToken = function(token) {
-    remoting.xhr.start({
+    new remoting.Xhr({
       method: 'GET',
       url: remoting.settings.DIRECTORY_API_BASE_URL + '/@me/hosts',
-      onDone: parseHostListResponse,
       oauthToken: token
-    });
+    }).then(parseHostListResponse);
   };
   remoting.identity.getToken().then(onToken, remoting.Error.handler(onError));
 };
@@ -61,13 +60,12 @@ remoting.HostListApiImpl.prototype.put =
         'publicKey': hostPublicKey
       }
     };
-    remoting.xhr.start({
+    new remoting.Xhr({
       method: 'PUT',
       url: remoting.settings.DIRECTORY_API_BASE_URL + '/@me/hosts/' + hostId,
-      onDone: remoting.xhr.defaultResponse(onDone, onError),
       jsonContent: newHostDetails,
       oauthToken: token
-    });
+    }).then(remoting.Xhr.defaultResponse(onDone, onError));
   };
   remoting.identity.getToken().then(onToken, remoting.Error.handler(onError));
 };
@@ -82,12 +80,11 @@ remoting.HostListApiImpl.prototype.put =
 remoting.HostListApiImpl.prototype.remove = function(hostId, onDone, onError) {
   /** @param {string} token */
   var onToken = function(token) {
-    remoting.xhr.start({
+    new remoting.Xhr({
       method: 'DELETE',
       url: remoting.settings.DIRECTORY_API_BASE_URL + '/@me/hosts/' + hostId,
-      onDone: remoting.xhr.defaultResponse(onDone, onError),
       oauthToken: token
-    });
+    }).then(remoting.Xhr.defaultResponse(onDone, onError));
   };
   remoting.identity.getToken().then(onToken, remoting.Error.handler(onError));
 };
@@ -99,14 +96,14 @@ remoting.HostListApiImpl.prototype.remove = function(hostId, onDone, onError) {
  *
  * @param {function(Array<remoting.Host>):void} onDone
  * @param {function(!remoting.Error):void} onError
- * @param {XMLHttpRequest} xhr
+ * @param {remoting.Xhr.Response} xhrr
  * @private
  */
 remoting.HostListApiImpl.prototype.parseHostListResponse_ =
-    function(onDone, onError, xhr) {
-  if (xhr.status == 200) {
+    function(onDone, onError, xhrr) {
+  if (xhrr.status == 200) {
     var response = /** @type {{data: {items: Array}}} */
-        (base.jsonParseSafe(xhr.responseText));
+        (base.jsonParseSafe(xhrr.responseText));
     if (!response || !response.data) {
       console.error('Invalid "hosts" response from server.');
       onError(remoting.Error.UNEXPECTED);
@@ -129,7 +126,7 @@ remoting.HostListApiImpl.prototype.parseHostListResponse_ =
       onDone(hosts);
     }
   } else {
-    onError(remoting.Error.fromHttpStatus(xhr.status));
+    onError(remoting.Error.fromHttpStatus(xhrr.status));
   }
 };